The invention relates to an arrangement and a method for measuring the rigidity of flat items according to the preamble of the independent patent claims.
It is necessary for the processing of letters, postcards and similar flat items in automatic letter sorting systems to measure the rigidity and the thickness of the items, because these letter sorting systems can only properly process items having specific predetermined parameters. In principle, such measurements can be carried out mechanically by means of a lever with a feeler roller and an inductive sensor. But at high transport speeds of, e. g., greater than 2.9 m/s, undesirable vibrations occur, so that rigidity and thickness cannot be determined accurately and separately with this functional principle. Moreover, a mechanical rigidity measurement requires much space and, like all mechanical arrangements, it is subject to increased wear. The aforesaid applies, in particular, to objects with uneven thickness or rigidity.